Compress a PDF Without Wrecking Readability
How much smaller will your PDF get?
Create a smaller PDF for an upload form, email attachment or archive. Compression results depend on the images, fonts and other content already stored in the source, so some files shrink more than others. Check small text, scanned pages and illustrations in the downloaded result. Keep the original when print quality or later editing matters.
Cost: Free to use. File size and usage limits apply.
How to compress a PDF
Add one PDF
Click Choose PDF or drop a PDF of up to 200 MB on the preview. You can also pick a file from Uploads, including results from other PDF tools. If you drop several PDFs, only the first is used.
Start the optimization
Click Compress PDF. There is nothing to configure: every file gets the same lossless optimization pass.
Compare the sizes
The result opens in the preview, and the bar below it shows the new size. The Source PDF card still shows the size of the original.
Download the smaller file
Click Download compressed PDF. The result is also saved in Uploads, so other PDF tools can use it without a new upload. If the result is not smaller, keep your original.
Which PDFs get smaller
The optimizer only removes data that the pages don't need and stores the file's internal structure more compactly. How much that saves depends on how the PDF was made.
Files edited and saved many times
Some editors append every save to the end of the file, so old versions of changed pages stay inside. The optimizer writes only what the current document uses, and these leftovers can be large.
Documents assembled from several files
When the parts of a PDF each carry their own identical copy of a font or image, the optimizer can keep a single copy.
Text-heavy PDFs from older software
Files without compressed object streams store their structure as plain text. Packing it into compressed streams gives a modest saving, which matters most when the file has little image data.
Scans and photo-heavy PDFs
Images are copied unchanged: they are not downsampled or re-encoded. In our test, a one-page PDF holding a 2,400 × 2,400 px JPEG of about 1.9 MB stayed at about 1.9 MB. To shrink a scan, scan again at a lower resolution or in grayscale.
Files that are already optimized
If a PDF already uses compressed object streams, there is little left to gain and the result can even be a few bytes larger. PDF Info shows Using object streams: Yes for such files.
What stays the same and what changes
Nothing on the pages is re-rendered. Text stays selectable and searchable, images keep every pixel, and page size and page count don't change. Links, comments and bookmarks are kept, and so are the title, author, subject and keywords in the document properties.
A few technical details do change. The PDF producer property now names pdfcpu, the library that does the work. Very old files, for example PDF 1.3, are saved as PDF 1.7, because compressed object streams need at least PDF 1.5. Such outputs require a reader that supports PDF 1.7. If the original was saved with Fast Web View (linearized) for page-by-page loading in a browser, that arrangement is removed.
A digitally signed PDF cannot stay validly signed after compression, because the signature covers the exact bytes of the original file. Compress first, then sign.
Formats and limits
- Input format
- Output format
- One PDF with the same pages
- Maximum file size
- 200 MB
- Files per job
- 1 PDF
- Compression type
- Lossless: images and page content are not re-encoded.
- Password-protected PDFs
- PDFs that ask for a password when you open them cannot be compressed. Remove the password first with Unlock PDF. PDFs that only restrict printing or copying can be compressed and keep those restrictions.
- Processing
- On our servers with the pdfcpu PDF library. No external service is involved. A job can run for up to 15 minutes.
- Watermark
- None
- Storage
- Uploads and results are deleted automatically after 48 hours for guests and after 30 days for free accounts. Paid plans can keep files longer.
Frequently asked questions
Why is my PDF barely smaller, or even a few bytes larger?
Most of its size is probably images, which this tool leaves untouched, or the file was already optimized. The tool always returns the new file without comparing sizes, so check the size under the preview against the Source PDF card and keep whichever is smaller.
Can I choose a compression level or a target size in MB?
No. Every PDF gets the same lossless pass. Reaching a specific size usually means lowering image resolution or JPEG quality, and this tool never changes images.
Will small text or images look worse after compression?
Page content is not redrawn, and images are not re-encoded or downsampled. The original text data and image resolution remain; structural optimization does not add sharpness to a scan. The resulting file size depends on the resources and structure of the original PDF.
Should I compress before or after adding a password?
Compress first, then protect the result with Protect PDF. A PDF that needs a password to open cannot be compressed, so you would have to unlock it again.